NeXT DSP Memory Expansion Module

helf · October 06, 2009, 07:53:55 AM

wooo! exciting! First the relatively easy overclock mod and now the schematics to the DSP cache card. Now we just need the docs to the SCSI Controller

NeXTnewbe · October 06, 2009, 08:20:17 AM

ARGhhh!!

yes all new components IS6xWV1288DALL are limited to 4V or less, the original is 5V, so a resistor is required on the Vcc, not sure about the I/O and Address inputs,

I'm not the best one here, someone with a bit more experience in electronics can help

cuby · October 06, 2009, 08:30:06 AM

Quote from: "NeXTnewbe"ARGhhh!!

yes all new components IS6xWV1288DALL are limited to 4V or less, the original is 5V, so a resistor is required on the Vcc, not sure about the I/O and Address inputs,

I'm not the best one here, someone with a bit more experience in electronics can help

The output voltage on the data lines also has to be 5V-compliant, so you would need a (rather fast) level shifter. But see the parts in my message above, these should work.

-- Michael

NeXTnewbe · October 06, 2009, 08:40:27 AM

Cuby

sorry, but I have no clue about "level shifter" as my electronic are so rusted that I only can do the pure basics

Let me ask you something, let me finished the schematics based on the original, and if you want I can send it to you for your modification, if you are happy to help us

regarding the PCB, I have no skills for this, I would prefer to know if someone can volunteer to help on produce them, based on the schematics and the original dimensions (if two layers are good, why not), it could be even cheap to produce some to all interested in this little project

what do you think?

EDIT: I google the level shifter, I undesrtand the the basic concept, but not sure how to implement this?

Nitro · October 06, 2009, 11:13:05 AM

Quote from: "NeXTnewbe"I was the guy who made him remember your email Nitro, he mention that you have contacted him few years ago, but he was so busy that he totally forgot it.

When I saw your post I assumed that's what happened. Thanks for sending him a reminder.

Quote from: "NeXTnewbe"Nitro, please we need to add a disclaimer, and giving all credit to the original module to Tim and Joel for the module, this should be a "Must", to make sure we are on le legal side all the time.

I placed a copyright notice in the project folder. Tom's PDF file also contains his copyright notice in at least three places.

Quote from: "NeXTnewbe"Nitro, how can I upload information to the Filearchive? I will put more bits that I got regarding the module

Feel free to send documents and files to the admin e-mail account here and I'll move them to the project folder. I can also set up a temporary FTP account if you have files that are too large to e-mail.

Thank you to everyone involved in this project.

NeXTnewbe · October 06, 2009, 02:38:51 PM

:idea:

mm, well I just had a contact with Austin Semiconductors and I asked

"Hi I would like to know if your company still producing the static SRAM MT5C1008 128k x 8 Sram at 5V as new part and new condition"

they answer was

"Good afternoon. The MT5C1008 parts are standard, active productcurrently still in production. If you would like to obtain a quoteplease contact our authorized representative in the UK"

So seems that it would be possible to get the same type of memory used originally

I will like to order a sample to test a memory circuit made on a protoboard, but i will need to take the connections out form the board in a safe way to test the original design with those comoponents,

NeXTnewbe · October 07, 2009, 04:32:29 AM

I wonder if it would be possible to get something similar to this connector
but with 64 pin for the same type of socket use on the MB

can be use to test the DSP memory?

pentium · October 07, 2009, 08:41:37 AM

you mean some sort of SIMM adapter?
Why not just make a little PCB that breaks the slot out into 50-pin connectors or something?

NeXTnewbe · October 07, 2009, 09:05:19 AM

Quote from: "pentium"you mean some sort of SIMM adapter?
Why not just make a little PCB that breaks the slot out into 50-pin connectors or something?

simple, I don't have the time and the risk of building a PBC and have a shor circuit is too high

:cry:

Nitro · October 07, 2009, 11:14:46 PM

Quote from: "NeXTnewbe"
Quote from: "pentium"you mean some sort of SIMM adapter?
Why not just make a little PCB that breaks the slot out into 50-pin connectors or something?

simple, I don't have the time and the risk of building a PBC and have a shor circuit is too high

:cry:

Pentium brings up a good point.

Quote from: "NeXTnewbe"simple, I don't have the time

What? If you don't have the time then how do you expect to follow through on this?.

Quote from: "NeXTnewbe"and the risk of building a PBC and have a shor circuit is too high

I'm guessing a prototype will be necessary for testing. How do you hope to test this without actually plugging it in?

pentium · October 08, 2009, 02:20:44 AM

Quote
Pentium brings up a good point.

I have this whole SIMM-out-of-the-cube adapter planned (SIMM adapter converts into ribbon cables which run through an open slat in the back and to another board which converts it bask into a SIMM slot) but I jast have no way to draw it out as my proper CAD/PCB drafting system is down and I'm not approving any sort of MS paint drawing.

Why not just find a mono slab or something, take the top off and use that? You get direct assess to the slot.

NeXTnewbe · October 08, 2009, 04:57:19 AM

Quote from: "pentium"
Quote
Pentium brings up a good point.

Why not just find a mono slab or something, take the top off and use that? You get direct assess to the slot.

is hard to find in UK an mono slab, so your idea of having a SIMM out, is the think i want to test the memory in a protoboard, to test the components and the memory design

this is more cheap that burn a SIMM memory pbc for every design, Pentium are you able to build one or two

I'm going to ask for some sample memory modules, if we get this running and if the original design works with some new components, I may buy some and then if we can get a SIMM pbc we can just ship it to those interested in get a DSP memroy module

what do you think?

pentium · October 08, 2009, 07:23:03 AM

If I could get access to some blank SIMMS that only have the pads at the bottom I'm quite sure I could make up a few of these '"outside the computer" slots/boards you want. Unfortunatly I don't know where to make blank SIMMs.

NeXTnewbe · October 08, 2009, 07:37:44 AM

Quote from: "pentium"If I could get access to some blank SIMMS that only have the pads at the bottom I'm quite sure I could make up a few of these '"outside the computer" slots/boards you want. Unfortunatly I don't know where to make blank SIMMs.

:cry: :cry: :cry: :cry: :cry: :cry: :cry: :cry: :cry: :cry: :cry: :cry: :cry: :cry: :cry: :cry:

cuby · October 08, 2009, 08:05:53 AM

Quote from: "pentium"If I could get access to some blank SIMMS that only have the pads at the bottom I'm quite sure I could make up a few of these '"outside the computer" slots/boards you want. Unfortunatly I don't know where to make blank SIMMs.

You could try to find some old Mac IIfx SIMMs - these also have 64 pins and fit into the DSP RAM slot (tried that yesterday) - and desolder the DRAM chips. However, with 35ns access time, manual wiring of the SRAMs might cause lots of trouble due to differing signal run time, signal crosstalk etc. But it might be worth a try.

-- Michael